The tentorial nerves and localization of intracranial pain in man

Abstract

The rich plexus of dural nerves, derived from the ophthalmic division of the trigeminal nerve and called by Arnold the tentorial nerves, forms a major contribution to innervation of intra- cranial structures. In contrast to the middle meningeal nerves, the tentorial nerves are related to cerebral veins and dural venous sinuses rather than arterial structures. Evidence from both anatomic studies and stimulation responses at operation indicates that the innervation of cortical veins entering the lateral and superior longitudinal sinuses is derived from the tentorial nerves coming from the first division of the trigeminal nerve. Local anesthetic solution injected into the dura of the falx and torcular regions abolishes pain from stimulation of these venous structures. Pain induced by traction of the venous structures of the middle fossa and by traction on the middle cerebral arterial vessels can be relieved by injection of Novocain (procaine) into the trigeminal ganglion. There is some evidence that, here again, the first division of the trigeminal nerve is mainly implicated. The fact that many of the dural nerve fibers are myelinated, with a diameter of 2 to 6 u, suggests that they subserve some function other than pain sensibility. Their close anatomic relationship to venous structures indicates that they may serve as afferent nerves contributing to vaso-motor function. In view of the derivation of the tentorial nerves from the ophthalmic division of the fifth nerve and their distribution to structures other than the tentorium, the term recurrent ophthalmic nerves," as originally suggested by Henle, might well be used. Nocuous stimulation of these nerves inside the head gives pain referred to the eye or forehead corresponding to the regions supplied by the main cutaneous branches of the ophthalmic division of the trigeminal nerve. Injection of anesthetic agent into the dura supplied by the tentorial nerves or into the trigeminal ganglion itself in the middle fossa serves as a valuable adjunct in carrying out intracranial procedures under local anesthesia. The effectiveness of these injections appears to depend upon blocking the sensory nerve fibers of the ophthalmic division of the trigeminal nerve.